Like a lot of folks eating primarily or only plants, I dislike eating animals because I empathize with animals and feel bad about their suffering from raising them for food.
That said, how much of the suffering involved in meat consumption actually comes from the animal whose meat is consumed?
What I'm thinking about is that eating animals is O(10) times less efficient at providing calories than eating plants. This suggests that if more than 0.1 units of suffering (assuming the animal being eaten suffers 1 unit) are produced in the production of plants for food, then the suffering caused by eating meat is dominated not by the suffering of the animal being eaten but by the suffering caused in order to produce the food.
Obviously some of this is going to be hard to pin down. For example, depending on how you weigh the suffering of insects and how much pesticides are used to grow feed stock of the meat being consumed may cause wild swings in estimates, but I'd nonetheless be interested in seeing what models people have of how much suffering is caused. This might also make a suffering-oriented case for better meat choices among those who eat meat anyway. For example, maybe organic beef causes O(100) times less suffering than conventional beef because 100 times fewer insects suffer in its production?
So, any thoughts on this, what I might call the "iceberg" of suffering caused by eating meat?
That's a good point about how much they are affected. If only around 10x as many wild land vertebrates are affected, I think it's pretty reasonable to believe that the effects on farmed land vertebrates are more important without thinking too much about the specifics, given how bad chicken lives seem to be on average. However, if you think a decent share of animal suffering is in dying, then wild vertebrate population effects could easily dominate. I think it's suspicious at around 100x, and would want to see more details about the magnitudes and directions of the effects on wild land vertebrates.
This is all before considering land invertebrates, but for someone with a lot of moral uncertainty about their moral weight, maybe the most sensible thing to do would be to also support an effective insect welfare/anti-insect farming charity. You could make sure you're net positive in expectation for both land vertebrates and land invertebrates with a portfolio of interventions.
And then we also need to look at aquatic animals.
Good to know about reptiles. That high end was surprising to me, given that I hardly ever see reptiles (in Canada, though!).